Abstract

Electron beam lithography and reactive ion etching have been used to pattern micron-size magnetic elements in the free layer of spin-tunnel junctions. The magnetization reversal processes of elements with dimensions in the range from 15x1 mu m(2) to 1x1 mu m(2) have been studied using Lorentz microscopy in the transmission electron microscope. Under the application of a field parallel to the bias direction, elongated elements reverse by the growth and subsequent annihilation of a quasiperiodic domain structure which evolves from the ends of the elements. Similar processes occur in both halves of a magnetization cycle. By contrast, the reversal of square elements involves the formation of more complex domain structures which differ significantly according to the direction in which the field in applied.

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